Storage arrangement for liquefied gas

ABSTRACT

An insulated large-scale container for liquefied gases at cryogenic temperatures is provided with a pressure-tight roof structure from which a horizontal ceiling structure is supported on hangers, the ceiling structure comprising a number of insulated panels which are so supported on the hangers that they are free to expand and contract under large temperature variations by moving laterally relative to each other and to their hangers, the ceiling as a whole being also free to have a limited movement relative to the walls of the container.

United States Patent Jackson [54] STORAGE ARRANGEMENT FOR LIQUEFIED GAS [72] Inventor: Robert G. Jackson, l-lornchurch, England [73] Assignee: Conch-International Methane Limited,

Nassau, Bahamas 221 Filed: Sept. 14, 1970 211 Appl.No.: 71,911

[30] Foreign Application Priority Data Oct. 31, 1969 Great Britain ..53,380/69 [52] US. Cl ..220/10, 62/45, 220/9 LG [51] Int. Cl ..B65d 7/22 [58] Field of Search ..220/9 LG, 10, 18, 15, 26 R,

[56] References Cited UNITED STATES PATENTS 1,674,039 6/1928 Glass ..220/26R 1,742,120 12/ 1 929 Afonin 220/ 26 R 2,006,505 7/1935 Lentschewsky.. ...220/26 R 3 ,249,251 5/1966 Nachshen ..220/18 Mar. 14, 1972 3,352,443 1 1/1967 Sattelberg et al ..220/9 LG 3,416,325 12/1968 Nelson ..220/9 LG 3,538,661 11/1970 Nelson..... 220/9 LG X 3,559,835 2/1971 Lange ..220/10 3,570,700 3/1971 Yamamoto ..220/10 FOREIGN PATENTS OR APPLICATIONS 1,081,644 8/ 1967 Great Britain ..220/9 LG 1,109,255 4/1968 Great Britain ..220/9 LG Primary Examiner-Joseph R. Leclair Assistant Examiner.lames R. Garrett AttorneyMax L. Libman [57] ABSTRACT An insulated large-scale container for liquefied gases at cryogenic temperatures is provided with a pressure-tight roof structure from which a horizontal ceiling structure is supported on hangers, the ceiling structure comprising a number of insulated panels which are so supported on the hangers that they are free to expand and contract under large temperature variations by moving laterally relative to each other and to their hangers, the ceiling as a whole being also free to have a limited movement relative to the walls of the container.

11 Claims, 5 Drawing Figures PATENTEUMARMIBYZ v 3,648,880

SHEET 1 OF 3 U n w" l ll fl ll llllllll 1x Yltyil 9 I nvenlor ROberBf G. .70 c/(5 n y fl hm Attorney PATENTEBMAR 14 1972 3. 648 880' SHEET 2 UF 3 Inventor Faber? G. Jbckson STORAGE ARRANGEMENT FOR LIQUEFIED GAS The invention relates to storage arrangements for liquefied gases, particularly liquefied natural gas or methane and liquefied petroleum gases such as ethane, propane, butane, ethylene and propylene.

In the specification the expression liquefied gas means liquid which boils at atmospheric pressure at a temperature below the ambient temperature.

From US. Pat. No. 3,159,006, it is known to provide a storage arrangement for liquefied gases which includes an insulated storage space having a pressuretight roof structure from which an insulated layer or ceiling is suspended by suitable brackets or hangers. The storage arrangement described is of the so-called inground storage type and the roof and ceiling structure described in said Patent is particularly applicable to this type of storage in that the periphery of the ceiling is located in a trench extending around the mouth of the storage hole. Also, because of the sizes presently contemplated for storage reservoirs, they could well be of the order of 50 meters in diameter, it will be appreciated that it would be extremely difficult to support the ceiling only from the hangers since the general nature of suitable insulating materials is such that it would be desirable to provide some support structure for the ceiling other than the hangers. As soon as one contemplates the use of a support structure difficulties arise in that suitable structural materials of reasonable cost in general have a relatively high-co-efficient of expansion and hence, on cooldown to operating temperature, contraction of the periphery of the ceiling support structure would tend to open an appreciable gap between said periphery and the wall of the storage, thus reducing considerably the insulation efficiency.

The object of the invention is to provide a storage arrangement having a pressuretight roof structure and an insulated ceiling arrangement broadly as discussed above which is applicable to a variety of types of storage, for example aboveground and inground and which utilizes a support structure for the ceiling whichever comes the difficulty referred to above.

Thus, in accordance with this invention, a storage arrangement for liquefied gas of the kind including an insulated storage space having a pressuretight roof structure which is substantially uninsulated and an insulated ceiling suspended from the roof structure via hangers, is characterized in that the ceiling is in the fonn of an insulated structure which extends horizontally over the storage space, and said ceiling structure comprises a number of insulated individual panels which are supported such that, if subjected to significant temperature variations, they are free to move relative to each other and to their hangers.

The ceiling structure may comprise a lattice framework attached to the hangers, said framework including individual frame members which connect between two hangers, each connection being in the form of a sliding joint whereby said individual frame members are free to move relative to their respective hangers, the insulated panels being supported on the said framework.

Alternatively, the panels of the ceiling structure may be in the form of trays filled with insulation material and arranged in side-by-side relationship, in which case each panel extends between at least three hangers, the trays being so shaped as to provide corners equal in number to the hangers to which the panel is to be attached, and a pair of spaced plates is attached to each hanger in which the appropriate corner of a panel is located.

The insulation material may be bonded to the panels either prior to or after assembly of the panels in the ceiling structure.

Conveniently, each hanger may be attached to the ceiling structure via a spacer which is of a material having a higher coefficient of expansion than the hanger, the relative lengths and the connection between said spacer and said hanger being such that, if subjected to significant temperature variations, the relative movement which takes place between each hanger and its spacer is such as to maintain the ceiling height substantially constant.

A storage arrangement in accordance with this invention may be aboveground or inground.

In order that the invention may be readily understood and further features made apparent, an aboveground storage arrangement in accordance with the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary sectional elevation of the aboveground storage arrangement;

FIG. 2 is a diagrammatic plan view of the roof and ceiling structures;

FIG. 3 is a sectional detail through the ceiling;

FIG. 4 is an enlarged perspective view showing the attachment of the hanger to the ceiling structure; and

FIG. 5 is a view similar to FIG. 4, showing an alternative attachment of the hanger to the ceiling structure.

Referring to FIG. 1, the aboveground storage arrangement comprises a main enclosing vessel 1 having a metal bottom, not shown, a metal wall 2 and a domed roof 3. The inner surface of the bottom and wall of the enclosing vessel 1 is lined with insulation 4. The inner surface of the insulation supports a metal membrane tank 5, the top of which stops short of the roof 3 of the enclosing vessel 1. In this embodiment the insulation 4 may be in the form of wooden boxes filled with a loose granular material, such as PERLITE (Reg. Trade Mark). The upper end of the insulation 4 is terminated at the level of the top of the membrane tank 5 and two layers of insulation material 6 are bonded to the upper surface of the insulation 4, these layers extending horizontally in between the top of the tank 5 and the wall of the enclosing vessel. A strip 7 of expanded aluminum is bonded between the upper surface of the insulation 4 and the lower surface of the lower insulation layer 6 and a crack breaker 8, e.g., a layer of paper or hessian, is embedded near the upper surface of the upper layer of insulation 6.

Referring also to FIG. 2, the hangers 9 are suspended from the roof 3 in a square lattice pattern and support the ceiling structure 10 at their lower ends. In one arrangement, as shown particularly in FIG. 4, the ceiling structure comprises a lattice framework 11 comprising a number of individual frame members 12, each frame member extending between a pair of adjacent hangers 9. The lower end of each hanger 9 is provided with a cruciform-shaped tubular housing 13 and a frame member 12 is slidable mounted within each limb 14 of the housing 13. The frame members 12 are somewhat shorter than the distance between each pair of hangers and are fitted to the housings 13 by sliding one end fully into one of the limbs 14 of one hanger and then reversing the sliding movement to fit the other end of the frame member 12 into the appropriate limb 14 of the other hanger. Bolts 15 are then fitted into each limb to maintain the ends of the frame members 12 within the limbs 14, of their respective housings 13. A panel 16 is provided for each space left between the lattice framework and each panel is preferably of expanded aluminum which is bent at its edge to provide an upstanding wall 17, and a marginal flange 18 which rests on the upper surfaces of the frame members 12 defining said space. The walls 17 and flange 18 are cutback at the corners of the panel trays so formed so as not to obstruct the limbs 14 of the housings 13. This embodiment provides a square lattice arrangement but it will be appreciated that a triangular lattice could also be used, the panel 16 being shaped to suit the particular lattice chosen. Each panel tray 16 has two layers of insulation material 19 bonded thereto as shown in FIG. 1. This insulation material may be of polyurethane foam sprayed into the trays. Preferably a crack breaker layer is laid in each panel tray 16 prior to the layers of insulation 19 being applied, the crack breaker layer preventing the foam from escaping through the spaces of the expanded aluminum. The layers of insulation may be applied either prior to assembly of the panels in the ceiling structure 10 or after said assembly. An I-beam 21 extends round the periphery of the ceiling structure 10 to provide strength to the structure; this I- beam may be suitably fastened to frame members 12.

The periphery of the ceiling structure 10 conforms to the periphery of the membrane tank 5 and is so located over said tank that its insulation layers 19 are at the same level as the insulation layers 6 covering the main wall insulation 4. A gap 22 is left between the ceiling structure and the layers of insulation 6 to allow for relative movement during temperature variations.

The lower end of each hanger 9 is attached to its housing 13 via a bracket 23, and a number of spacer strips 24 of flourinated hydrocarbon such as TEFLON (Reg. Trade Mark) are inserted between said lower end of the hanger and its bracket 23. The coefficient of expansion of the strips 24 is much higher than that of the hangers 9, which are preferably of metal, and the dimensions of the spacer strips and that part of its hanger which may be subjected to significant temperature variations, are so chosen as to maintain the ceiling structure suspended at a substantially constant height during temperature variations. Preferably, further insulation 25 is added above the insulation layers 6 and 19 (FIG. 1), this insulation being of a granular material, such as PERLITE. The gap 22 between the layers 6 and the ceiling structure is covered by a porous material 20, such as cotton, which is loosely folded. This porous material covering allows any boiloff gas accumulated in the membrane tank 5 to pass through to the roof space and also prevents the granular insulation 25 from falling into said tank. To provide further insulation in the roof space and to provide a boundary for the granular insulation 25, an expanded aluminum support structure 26 is supported close to the wall 2 of the enclosing vessel 1 and extends for a short distance parallel to the roof 3. The inner surface of this support structure has a layer 27 of insulation, such as polyurethane foam, spayed onto it.

The ceiling structure is centered over the membrane tank 5 by four centering devices 28 which are equally spaced round the ceiling structure and are attached to the I-beam 21. Each device 28 comprises a bell crank 29 pivoted at 30 to the I- beam and having a roller 31 at one end thereof which is arranged to engage the inner surface of the membrane tank 5 and a counterweight 32 at the other end thereof.

With reference to FIG. 3, a filling pipe 33 extends through the insulation layers 19 of the ceiling structure, this pipe passing through a tube 34 supported within the layers of insulation. A packing 35 of mineral wool is provided between said tube and said pipe which agains permits boiloff gas to escape to the roof space.

Referring to FIG. 5 in an alternative construction of the ceiling structure no lattice framework is provided and instead, each of the panels 16 is provided with a marginal tubular wall 36, the panel trays 16 so formed are preferably of aluminum sheet and the walls are provided by appropriate bending of the edges of the sheet. Each of the hanger brackets 23 is provided with a pair of spaced plates 37 which sandwich the common corners of four adjacent panels therebetween via a nut and bolt 38. In this arrangement spaces 39 may be left between the panel trays 16 to allow for relative movement and these spaces may be covered by further porous material for the reasons mentioned hereinbefore with regard to the gap 22.

In operation, as the tank is filled via pipe 33 with, for example, liquid natural gas, which is required to be maintained at a temperature of -l6l C. for it to retain its liquid state, as the liquid level rises the ceiling structure 10 will be subjected to progressively lower temperatures. Also, when filled and when in use temperature variations may occur in the vicinity of the ceiling structure 10, e.g., due to changes in liquid level. Although the ceiling panels 16 are of a material having a relatively low coefficient of expansion, nevertheless appreciable dimensional changes can occur at the operating temperatures envisaged. These dimensional changes are conveniently catered for by the panels 16 being free to move relative to each other and to the hangers 9, thus virtually eliminating, or at least reducing considerably, the stresses transmitted to the hangers 9 and the ceiling insulation layers 19 compared with a ceiling structure having a continuous lining.

An advantage of this storage arrangement is that, particularly in the case where the panels 16 are provided with their insulation layers 19 prior to assembly in the ceiling structure, the panels would be sufficiently strong to support an appreciable weight. Thus, the panels 16 could be assembled in the ceiling structure from the roof space, thus eliminating the need for scaffolding within the tank during this operation.

A further advantage of this arrangement is that by choosing a suitable material for the insulation layers 19 covering the main wall insulation 4 these layers may provide a barrier to the liquid should the tank 5 be overfilled and the liquid level rise into the roof space. I

Although this embodiment has been described as having a membrane tank 5, it will be appreciated that the invention may be used with a free-standing tank design. With such a design, in the interest of economy, the space between the wall 2 and the tank 5 could be filled with loose granular insulation material, when the provision of the barrier layers 19 would be of particular advantage.

It will be appreciated that although the embodiment described is an aboveground storage arrangement the invention may be used in an in-ground storage arrangement.

It will also be appreciated that the enclosing vessel in the case of the aboveground storage arrangement may be of any suitable material, for example concrete. In the case of the inground storage arrangement, the storage hole may be lined with concrete.

It will further be appreciated that in the case of an in-ground storage arrangement the wall insulation 4 may be made thinner than that required for the aboveground arrangement, since the ground and/or the concrete lining will provide further insulation for the storage hole.

I claim:

1. a. A large-scale storage container for liquefied gas including a walled storage space,

b. said container having a gastight roof structure,

c. a generally horizontal ceiling structure suspended on hangers from said roof structure and extending across the top of said storage space,

d. said ceiling structure comprising a plurality of insulated panels subject to horizontal expansion and contraction due to temperature changes in said container,

e. said panels being individually supported on said hangers for limited individual lateral contraction and expansion relative to each other and to the hangers.

2. A storage arrangement according to claim 1,

f. wherein at least three centering devices are attached to the lower surface of the ceiling structure and spaced around its periphery,

g. each device comprising a bell crank pivoted at its apex portion to the ceiling structure and having a roller at one end thereof to engage the wall of the storage space and a counterweight at the other end thereof.

3. A storage arrangement according to claim I,

f. wherein each hanger is attached to the ceiling structure via a spacer which is of a material having a higher coefficient of expansion than the hanger, the relative dimensions and the connection between the spacer and hanger being such that, if subjected to significant temperature variations, the relative movement which takes place between each hanger and its spacer is such as to maintain the ceiling height substantially constant.

4. A storage arrangement according to claim 1,

f. wherein the ceiling structure comprises a lattice framework attached to the hangers,

g. said framework including individual frame members which connect between two hangers,

h. each connection being in the form of a sliding joint whereby said individual frame members are free to move relative to their respective hangers,

i. the insulated panels being supported on said framework.

5. A storage arrangement according to claim 4,

j. wherein the panels are in the form of trays filled with the insulation material,

k. each tray fitting into one space of the lattice framework and having a marginal flange which is supported on the upper surfaces of the frame members defining said space.

6. A storage arrangement according to claim 5,

1. wherein the panels are of expanded aluminum.

7. A storage arrangement according to claim 1,

f. wherein the ceiling panels are in the form of trays filled with the insulation material and are arranged in side-byside relationship,

g. each panel supported by at least three hangers,

h. the trays being so shaped as to provide corners equal in number to the hangers to which the panel is to be attached,

i. and a pair of spaced plates attached to each hanger in I which the appropriate corner of a panel is located. 8. A storage arrangement according to claim 7, j. wherein each panel tray is formed from sheet material, the edges of the sheet being bent to provide a tubular wall. 9. A storage arrangement according to claim 7, wherein any gaps between said panels are covered by a layer of porous material such as cotton.

10. A storage arrangement according to claim I,

f. the container comprising an enclosing vessel which is lined internally with insulation and which includes said pressuretight roof structure,

g. wherein the wall insulation is of a material not providing a barrier to liquefied gas, e.g., granular material, and stops short of the roof structure,

h. the upper surface of this insulation having at least one insulation layer acting as a barrier to liquefied gas,

i. a metal tank defining said storage space being disposed within the wall insulation,

j. and the ceiling structure being suspended over the tank at a level corresponding to said insulation layer.

1 l. A storage arrangement according to claim 10,

k. wherein a gap is left between the periphery of the ceiling structure and the adjacent part of the storage space,

1. and a layer of porous material such as cotton covers this gap. 

1. A. A large-scale storage container for liquefied gas including a walled storage space, b. said container having a gas-tight roof structure, c. a generally horizontal ceiling structure suspended on hangers from said roof structure and extending across the top of said storage space, d. said ceiling structure comprising a plurality of insulated panels subject to horizontal expansion and contraction due to temperature changes in said container, e. said panels being individually supported on said hangers for limited individual lateral contraction and expansion relative to each other and to the hangers.
 2. A storage arrangement according to claim 1, f. wherein at least three centering devices are attached to the lower surface of the ceiling structure and spaced around its periphery, g. each device comprising a bell crank pivoted at its apex portion to the ceiling structure and having a roller at one end thereof to engage the wall of the storage space and a counterweight at the other end thereof.
 3. A storage arrangement according to claim 1, f. wherein each hanger is attached to the ceiling structure via a spacer which is of a material having a higher co-efficient of expansion than the hanger, the relative dimensions and the connection between the spacer and hanger being such that, if subjected to significant temperature variations, the relative movement which takes place between each hanger and its spacer is such as to maintain the ceiling height substantially constant.
 4. A storage arrangement according to claim 1, f. wherein the ceiling structure comprises a lattice framework attached to the hangers, g. said framework including individual frame members which connect between two hangers, h. each connection being in the form of a sliding joint whereby said individual frame members are free to move relative to their respective hangers, i. the insulated panels being supported on said framework.
 5. A storage arrangement according to claim 4, j. wherein the panels are in the form of trays filled with the insulation material, k. each tray fitting into one space of the lattice framework and having a marginal flange which is supported on the upper surfaces of the frame members defining said space.
 6. A storage arrangement according to claim 5,
 7. A storage arrangement according to claim 1, f. wherein the ceiling panels are in the form of trays filled with the insulation material and are arranged in side-by-side relationship, g. each panel supported by at least three hangers, h. the trays being so shaped as to provide corners equal in number to the hangers to which the panel is to be attached, i. and a pair of spaced plates attached to each hanger in which the appropriate corner of a panel is located.
 8. A storage arrangement according to claim 7, j. wherein each panel tray is formed from sheet material, the edges of the sheet being bent to provide a tubular wall.
 9. A storage arrangement according to claim 7, wherein any gaps between said panels are covered by a layer of porous material such as cotton.
 10. A storage arrangement according to claim 1, f. the container comprising an enclosing vessel which is lined internally with insulation and which includes said pressure-tight roof structure, g. wherein the wall insulation is of a material not providing a barrier to liquefied gas, e.g. granular material, and stops short of the roof structure, h. the upper surface of this insulation having at least one insulation layer acting as a barrier to liquefied gas, i. a metal tank defining said storage space being disposed within the wall insulation, j. and the ceiling structure being suspended over the tank at a level corresponding to said insulation layer.
 11. A storage arrangement according to claim 10, k. wherein a gap is left between the periphery of the ceiling structure and the adjacent part of the storage space, 